PGI User Forum

[kzhu]

Hi all,

I used pgc++ to create the object files, (with -fPIC flag for all object files). At the linking stage, I received the following error message.

[mkcolg]

Hi Kevin,

I typically see this error when you have a very large static array (>2GB) in the code. In this case, you need use the medium memory model (-mcmodel=medium).

If that doesn't work, I'll need you to send a report to PGI Customer Service (trs@pgroup.com) and include a reproducing example to determine the cause, or the the following information.

The output from:
pgc++ -c t.c -dryrun

As well as the post processed source files:
pgc++ -C -E <user_flags> xxx.c -o outx.i
pgc++ -C -E <user_flags> yyy.c -o outy.i
pgc++ -C -E <user_flags> zz.c -o outz.i

Note that pgc++ doesn't accept the "-pthread" flag, hence you should be getting a compilation error if you use it.

- Mat

[kzhu]

Hi Mat,

Thank you for the pointers.

For the record, the object files are less than 2~GB. I tried the -mcmodel flag anyway, but it was not compatible with -fPIC that I needed.

Surprisingly, I did not get a compilation error with "-pthread". To be on the safe side, I removed the -pthread flag when generating the object files. This did not affect the "relocation R_X86_64_PC32 against ... " error at the linking stage.


Kevin

[jtull]

Always put the *.o files before any libs in a link line creating the shared libs.

xxx.o yyy.o and zzz.o should be compiled -fPICto be put into a shared library.

Objects compiled -mcmodel=medium can never be put into a shared library -
the have a 64-bit offset field, and linking with 32-bit offset fields causes
'relocation R_X86_64_PC32 truncated to fit' messages.

The only objects that can be linked with objects compiled -mcmodel=medium are

1. other objects compiled -mcmodel=medium
2. objects compiled -fPIC and put into a shared lib.

====================================
if you can avoid -mcmodel=medium in your main code, you are better off.

if you require large arrays, dynamically allocated them at runtime.

routines in shared libs like foo

subroutine foo(x,y,z,n)
integer*8 n,i
real*8 x(n), y(n), z(n)
do i=1,n
z(i)-x(i)+y(i)
end do
return
end subroutine foo

should be compiled
-fPIC -Mlarge_arrays

before being put into a shared library.

Then you can pass small or large arrays to foo, and things
should work as expected.